1. Field of the Invention
The present invention relates to a silicone gasket/packing material composition which cures at room temperature to produce an elastomeric product useful as a gasket or packing material.
2. Prior Art
A number of fixed-shape materials are used in the art as gasket and packing materials, for example, cork, asbestos paper, semimetallics, cork rubber, etc., for use in the automobile industry, electrical machinery and appliance industry and machine industry. However, these fixed-shape gasket and packing materials are expensive, their inventory control is troublesome, and they cannot be used for parts in which three surfaces meet.
On the other hand, a method is employed in the automobile industry for sealing in the vicinity of the engine in which a room temperature-curing silicone rubber composition is applied in its uncured state to a sealing surface. Curing at room temperature with pressing produces a silicone rubber layer adhering to the substrate at the sealing surface. Adhesive room temperature-curing silicone rubber compositions have been proposed for use in this application for example, refer to Japanese Patent Publication Number 46[1971]-11272, published Mar. 22. 1971, to Ichiro Hashishiro and Susumu Horii. This publication describes the use of an adhesive, room-temperature-curable silicone rubber composition useful in the automobile industry, especially as gasket material and packing for car engines. However, the products produced from the compositions of Hashishiro et al are not resistant to hot hydrocarbon oil, with the result that it suffers from oil leaks in long-term usage. For this reason, such compositions are unsatisfactory as a gasket material or packing material.
Schiller et al in U.S. Pat. No. 4,191,817, issued Mar. 4, 1980 describes curable compositions which can be stored under anhydrous conditions but when exposed to atmospheric moisture cross-link to form elastomers. The compositions of Schiller et al consist to diorganopolysiloxanes having terminal condensable groups, a silicon compound containing at least three hydrolyzable groups which are either amino bonded to silicon via a silicon-nitrogen bond and oxime bonded to silicon via a silicon-oxygen bond, and as an adhesion additive, an organosilicon compound which has at least one amino group and at least one silicon-oxygen bond. These compositions of Schiller et al can contain fillers and other components including organopolysiloxane resins such as those consisting of (CH.sub.3).sub.3 SiO.sub.0.5 and SiO.sub.2 units. Although the adhesion of the compositions of Schiller et al are improved over having no additive, such compositions are deficient when exposed to coolant used in automobile radiators.